Multi-level synchrotron radiation-based microtomography of the dental alveolus and its consequences for orthodontics.

Multilevel synchrotron radiation-based microtomography has been performed on a human jaw segment obtained at autopsy by cutting increasingly smaller samples from the original segment. The focus of this study lay on the microstructure of the interface between root, periodontal ligament (PDL) and alveolar bone in order to find an answer to the question why alveolar bone remodels during orthodontic loading, when the associated stress and strain levels calculated with finite element analyses are well below the established threshold levels for bone remodeling. While the inner surface of the alveolus appears to be rather smooth on the lower resolution scans, detailed scans of the root-PDL-bone interface reveal that on a microscopical scale it is actually quite rough and uneven with bony spiculae protruding into the PDL space.

Morphological and molecular evidence converge upon a robust phylogeny of the megadiverse Holometabola.

We present the largest morphological character set ever compiled for Holometabola. This was made possible through an optimized acquisition of data. Based on our analyses and recently published hypotheses based on molecular data, we discuss higher-level phylogeny and evolutionary changes.

In Situ X-Ray Scattering Studies of Poly(ε-caprolactone) Networks with Grafted Poly(ethylene glycol) Chains to Investigate Structural Changes during Dual- and Triple-Shape Effect.

The dual- and triple-shape effects of multiphase polymer networks that contain two crystallizable chain segments have been assessed in situ by combining X-ray measurements with thermomechanical investigations. The studied polymer, named CLEG, is a multiphase polymer network of crystallizable poly(ε-caprolactone) (PCL) with grafted poly(ethylene glycol) (PEG) side chains. Wide-angle (WAXS) and small-angle X-ray scattering (SAXS) measurements were combined with temperature-controlled in situ tensile testing experiments.

Knowledge-based tailoring of gelatin-based materials by functionalization with tyrosine-derived groups.

Molecular models of gelatin-based materials formed the basis for the knowledge-based design of a physically cross-linked polymer system. The computational models with 25 wt.-% water content were validated by comparison of the calculated structural properties with experimental data and were then used as predictive tools to study chain organization, cross-link formation, and estimation of mechanical properties.

Influence of VEGF stimulated human macrophages on the proliferation of dermal microvascular endothelial cells: Coculture experiments.

Monocytes/macrophages are known to exhibit pro-angiogenic activities after VEGF stimulation. Recently, it was shown that VEGF stimulated macrophages can support growth of microvascular endothelial cells from the lung when both cell types were cocultured using a cell ratio of 1:1. However, endothelial cells can have different phenotypic characteristics and metabolism depending on the originating vascular bed and tissues, and only few data have been published regarding the regiospecific sensitivity of microvascular endothelial cells for angiogenic stimuli.

Polyfluorinated compounds in residential and nonresidential indoor air.

Indoor air concentrations of fifteen volatile per- and polyfluorinated compounds (PFCs) (five fluorotelomer alcohols (FTOHs), three fluorotelomer acrylates (FTAs), three perfluorinated sulfonamido ethanols (FASEs), and three perfluorinated sulfonamides (FASAs)) were determined in residential and nonresidential indoor air environments. Air samples were taken with passive samplers, consisting of XAD-4 impregnated polyurethane foam (PUF) disks in steel housings. Impregnated PUF disks were extracted by fluidized bed extraction (FBE) using methyl-tert-butyl ether/acetone (1:1) and analyzed by gas chromatography-mass spectrometry.

First health and pollution study on harbor seals (Phoca vitulina) living in the German Elbe estuary.

The Elbe is one of the major rivers releasing pollutants into the coastal areas of the German North Sea. Its estuary represents the habitat of a small population of harbor seals (Phoca vitulina). Only little is known about the health status and contamination levels of these seals.

Melt-processable hydrophobic acrylonitrile-based copolymer systems with adjustable elastic properties designed for biomedical applications.

Acrylonitrile-based polymer systems (PAN) are comprehensively explored as versatile biomaterials having various potential biomedical applications, such as membranes for extra corporal devices or matrixes for guided skin reconstruction. The surface properties (e.g.

Degradation of and angiogenesis around multiblock copolymers containing poly(p-dioxanone)- and poly(epsilon-caprolactone)-segments subcutaneously implanted in the rat neck.

The degradation behavior and the effect on angiogenesis of multiblock copolymers based on poly(p-dioxanone)- and poly(epsilon-caprolactone)-segments (PDC) were studied in vivo. PDC is a multifunctional biomaterial combining degradability and shape-memory capabilities. The "in vivo" degradation of PDC is characterized by a fragmentation occurring at the material tissue interface.

Critical hematocrit and oxygen partial pressure in the beating heart of pigs.

In cardiac surgery the substitution of lost blood volume by plasma substitutes is a common therapeutical approach. None of the currently available blood substitutes has a sufficient oxygen transport capacity. This can limit the functional integrity of the myocardium known as highly oxygen consumptive.

AB-polymer networks with cooligoester and poly(n-butyl acrylate) segments as a multifunctional matrix for controlled drug release.

Semi-crystalline AB-copolymer networks from oligo[(epsilon-caprolactone)-co-glycolide]dimethacrylates and n-butylacrylate have recently been shown to exhibit a shape-memory functionality, which may be used for self-deploying and anchoring of implants. In this study, a family of such materials differing in their molar glycolide contents chi(G) was investigated to determine structure-property functional relationships of unloaded and drug loaded specimens. Drug loading and release were evaluated, as well as their degradation behavior in vitro and in vivo.

Comparing techniques for drug loading of shape-memory polymer networks--effect on their functionalities.

A family of oligo[(epsilon-caprolactone)-co-glycolide]dimethacrylate (oCG-DMA) derived networks of different glycolide contents as well as precursor molecular weights has been synthesized by crosslinking oCG-DMA, providing matrices of different hydrophilicity, network density, and morphology at body temperature. Such networks were loaded with a hydrophilic model drug, ethacridine lactate, either before crosslinking or afterwards by swelling in drug solution. Disadvantageous alterations of the shape-memory functionality and degradation characteristics were observed only in few loaded materials.

Interaction of an antimicrobial peptide with membranes: experiments and simulations with NKCS.

We used Monte Carlo simulations and biophysical measurements to study the interaction of NKCS, a derivative of the antimicrobial peptide NK-2, with a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) membrane. The simulations showed that NKCS adsorbed on the membrane surface and the dominant conformation featured two amphipathic helices connected by a hinge region. We designed two mutants in the hinge to investigate the interplay between helicity and membrane affinity.

Effects of methyl-, phenyl-, ethylmercury and mercurychlorid on immune cells of harbor seals (Phoca vitulina).

Mercury (Hg) is present in the marine environment as a natural metal often enhanced through human activities. Depending on its chemical form, Hg can cause a wide range of immunotoxic effects. In this study, the influence of methyl-, ethyl- and phenylmercury as well as mercurychloride on immune functions was evaluated.

Cytocompatibility testing of cell culture modules fabricated from specific candidate biomaterials using injection molding.

Most polymers used in clinical applications today are materials that have been developed originally for application areas other than biomedicine. Testing the cell- and tissue-compatibility of novel materials in vitro and in vivo is of key importance for the approval of medical devices and is regulated according to the Council Directive 93/42/EEC of the European communities concerning medical devices. In the standardized testing methods the testing sample is placed in commercially available cell culture plates, which are often made from polystyrene.

Membrane association and selectivity of the antimicrobial peptide NK-2: a molecular dynamics simulation study.

In an effort to better understand the initial mechanism of selectivity and membrane association of the synthetic antimicrobial peptide NK-2, we have applied molecular dynamics simulation techniques to elucidate the interaction of the peptide with the membrane interfaces. A homogeneous dipalmitoylphosphatidylglycerol (DPPG) and a homogeneous dipalmitoylphosphatidylethanolamine (DPPE) bilayers were taken as model systems for the cytoplasmic bacterial and human erythrocyte membranes, respectively. The results of our simulations on DPPG and DPPE model membranes in the gel phase show that the binding of the peptide, which is considerably stronger for the negatively charged DPPG lipid bilayer than for the zwitterionic DPPE, is mostly governed by electrostatic interactions between negatively charged residues in the membrane and positively charged residues in the peptide.

Evaluation of a degradable shape-memory polymer network as matrix for controlled drug release.

Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for controlled drug release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications.

Amorphous phase-segregated copoly(ether)esterurethane thermoset networks with oligo(propylene glycol) and oligo[(rac-lactide)-co-glycolide] segments: synthesis and characterization.

Completely amorphous copoly(ether)ester networks based on oligo(propylene glycol) and oligo[(rac-dilactide)-co-glycolide] segments were synthesized by crosslinking star-shaped hydroxyl-telechelic cooligomers using an aliphatic low-molecular weight diisocyanate. Two different network architectures were applied exhibiting differences in the phase-separation behavior. For networks from oligo(propylene glycol)-block-oligo[(rac-lactide)-co-glycolide] triols (G(3)OPG-bl-OLG) only one glass transition was obtained.

Controlling the switching temperature of biodegradable, amorphous, shape-memory poly(rac-lactide)urethane networks by incorporation of different comonomers.

Biodegradable shape-memory polymers have attracted tremendous interest as potential implant materials for minimally invasive surgery. Here, the precise control of the material's functions, for example, the switching temperature T(sw), is a particular challenge. T(sw) should be either between room and body temperature for automatically inducing the shape change upon implantation or slightly above body temperature for on demand activation.

Metal-induced impairment of the cellular immunity of newborn harbor seals (Phoca vitulina).

The cellular immunity of newborn harbor seals and the influence of pollutants are rarely investigated. This study evaluated the lymphocyte proliferation using a lymphocyte proliferation test (LTT) to understand the dynamics of immune response in seal pups of varying ages from the moment they arrived in a seal center after active beaching until their release into wildlife 3 months later after rehabilitation. Moreover, the effect of various metals (Ag, Al, Au, Be, Cd, Co, Cr, Cu, different Hg compounds, Mo, Ni, Pb, Pd, Pt, Sn, Ti) on lymphocyte proliferation in terms of immunosuppression and hypersensitivity was investigated.

Microwave plasma surface modification of silicone elastomer with allylamine for improvement of biocompatibility.

The microwave plasma surface modification of silicone elastomer with allylamine was studied to improve the biocompatibility of the material. An effort was made to clarify the relationships among plasma conditions and surface chemical composition, physical surface properties and biocompatibility of material, as well as the stability of plasma deposited layers. ATR-IR, XPS, Ellipsometry measurements, and contact angle measurements were used to investigate the changes of surface.